Compressed gas circuit breaker having coupled variable-volume high and low pressure chambers for expediting gas pressure recovery in the high pressure chamber

ABSTRACT

A columnar type electrical circuit breaker of the gas blast type includes a switching chamber containing the breaker contacts, together with a high gas pressure readiness tank, and a low gas pressure tank and a blast valve mounted at the top of the column. When the blast valve is opened and the switch contacts are disengaged, the contacts are swept over by the high pressure gas discharged through the blast valve from the high pressure tank into the switching chamber, the gas then flowing into the low pressure tank and thence ultimately back into the high pressure tank to replenish the latter after passage through a compressor located at the lower end of the column. The low pressure tank is provided with a movable wall portion acting as a piston which is rigidly connected with a piston forming one end wall of the high pressure tank such that when the gas is discharged into the low pressure chamber it actuates the movable wall piston thereof in such direction as to increase the volume of the low pressure tank and simultaneously, and to the same extent, decrease the volume of the high pressure tank, thus maintaining the gas pressure in the latter at its initial high value and in readiness for a subsequently and rapidly reoccurring switching out operation.

[ 1 .lune 19, 1973 United States Patent 1 Clerc et al.

[57] ABSTRACT A columnar type electrical circuit breaker of the gas blast type includes a switching chamber containing the breaker contacts, together with a high gas pressure RECOVERY IN THE HIGH PRESSURE readiness tank, and a low gas pressure tank and a blast CHAMBER valve mounted at the top of the column. When the blast valve is opened and the switch contacts are disengaged, the contacts are swept over by the high pressure gas [75] Inventors: Henri Clerc; Dieter Floessel, both of Fislisbach, Switzerland discharged through the blast valve from the high pres- [73] Aktiengesellschaft Brown, Boveri & sure tank into the switching chamber, the gas then flowing into the low pressure tank and thence ultimately back into the high pressure tank to replenish the Assignee:

Cie., Baden, Switzerland Nov. 18, 1971 Appl. N04: 199,869

[22] filed: latter after passage through a compressor located at the [21:]

lower end of the column. The low pressure tank is provided with a movable wall portion acting as a piston 200/148 B which is'rigidly connected with apiston forming one Holh 33/54 end wall of the high pressure tank such that when the 48 B l 48 R gas is discharged into the low pressure chamber it actuates the movable wall piston thereof in such direction [511 lm.cl......'.... [5 8] Field of Search as to increase the volume of the low pressure tank and simultaneously, and to the same extent, decrease the References Cited FOREIGN PATENTS OR APPLICATIONS 1,931,094

volume of the high pressure'tanlt, thus maintaining the 12/1970." -G y- 200/148 R gas pressure in the latter at its initial high value and in v g readiness for a subsequently and rapidlyreoccurring Primary Examiner-Robert S. Macon it hin out operation.

A ttorney Ralph B. Parker and Eugene .I-. Roberts 7 9 3 Claims, 1 Drawing Figure m a I I n I Patented June 19,, 19.73

This invention relates to an electrical circuit breaker of the so-called gas blast type wherein the contacts of the breaker are swept over by a blast of a gas which functions to quench the arc drawn by the contacts as they separate under load. In the particular type of breaker to which the present invention relates, the quenching gas is utilized in a so-called closed cycle by means of which the gas, for example SP is stored at high pressure in a readiness tank atop an insulating columnar support closely adjacent the chamber in which the switch contacts are located for immediate delivery to the contacts upon opening of a blast valve, there being a low-pressure tank into which the blast gas is returned after use at the contacts and there being a compressor interposed between the two tanks to replenish the pressurized gas discharged from the high pressure tank during'the switching process. The high and low pressuretanks carry the high potential of the line to which the switch is connected.

A columnar type gas blast switch is known from German Pat. No. 1,931,094 and a corresponding US. Pat. No. 3,678,234 wherein a readiness tank for the high pressure gas is disposed at high potential in the immediate proximity of the chamber in which the switching contacts are located. For quenching the arc, a blast valve is opened so that high pressure gas can flow through the hollow contacts into the low pressure tank. In order to ensure fast and possibly complete re-filling of the high pressure tank in cases of rapid disconnections during the relatively brief currentless pauses as they occur, for example, in a switching sequence with short interruptions, a storage tank for the gas, which is a ground potential, is associated with the high pressure readiness tank which is at high potential, and both tanks are connected with each other by means of a gas line having a large cross-section. The storage tank is constructed as a cylinder which contains a movable piston that-functions as an end wall of the cylinder, this 'piston being connected to another and smaller piston whichis located in an adjacent cylinder and subjected continuously to a high pressure from a high pressure storage source, e.g., a nitrogen high pressure bottle. During consumption of the high pressure gas from the readiness tank during a contact switching process, the smaller piston functionsto displace the larger piston in the storage tank in the direction to decrease the volume of the latter and hence restore the pressure of the gas in the readiness tank so that a second and rapidly following switching sequence has the benefit of the same high pressure of the quenching gas as was available upon the initial switching sequence; thus there is no reduction of switching power which otherwise would occur if the second switching out operation of the contacts had to take place with quenching gas at a lower pressure than that prevailingfor the first switching out operation. However, this arrangement is still relatively complicated because of the fact that the storage tank is located remotely from the readiness tank which ne cessitates use of a pressure gas line between them, and thus between ground andthe high potential of the circuit breaker to which the readiness tank is subjected.

The present invention is directed to a more practical and less expensive solution to the problem of maintaining the initial high pressure of the gas in the readiness tank for several rapidly reoccurring switching operations which take place automatically when the circuit breaker is unable to disconnect the circuit at the first switching out operation, e.g., due to a persistant shortcircuit condition. In accordance with the invention, the low pressure storage tank which is located adjacent the high pressure readiness tank from which high pressure gas is delivered to the circuit breaker contacts, is provided with a movable wall which functions as a piston, this movable wall being rigidly connected with a piston forming one end wall of the high pressure readiness tank, thearrangement being such that as the pistons are actuated, the resulting increase in the volume of the low pressure tank corresponds to the same decrease in volume of the high pressure tank.

A preferred embodiment of the invention will now be 1 described in detail and is illustrated in the accompanying drawing, the single FIGURE of which is a vertical central section through the upper portion of the columnar supported circuit breaker containing the switch contact chamber and the structurally integrated high pressure readiness tank, low pressure tank and interconnected piston components.

With reference now to the drawing, at the top of a hollow insulating support column 1 is arranged a high pressure readiness tank 2 to whichis joined the switch contact chamber 3 containing the switching contacts 15, 15a. The high pressure tank 2 storing gas at high pressure communicates through a duct 2a with one end of a cylinder 4 in'which is located a piston 5, the piston 5 being sealed at the inner wall of the cylinder so as to be gas-tight. The interior of cylinder 4, depending upon the position of piston 5 thus forms a variable volume which together with the duct 2a and fixed volume of the readiness tank 2 determine the overall volume of the latter and hence the pressure of the gas therein. Located atop the high pressure tank 2 and at the same high potential is the low pressure tank 6 which is terminated at the top by a bell-shaped, movable outer wall 7 which functions as a piston. The piston 5 and the movable outer wall 7 are rigidly interconnected by means of a rod 8. The bell-shaped outer wall 7 is sealinglyconnected to a fixed wall portion of the lowpressure tank 6 by means of a rolled hose diaphragm 9. Piston 5 is provided with an insulating linkage 10 which passes down through the columnar insulator 1, and

which serves, in known manner, to actuate a control switch by means of which a compressor located at the lower end of the column and at ground potential. is started. The compressor has not been illustrated, but the duct extending from the high pressure outlet of the compressor up through the insulator column 1 into the high pressure tank 2 is indicated at 11. The duct leading from the low pressure tank6 to the low pressure inlet side of the compressor has not been illustrated. The blast valve 13 for controlling the inlet to the switch contact chamber 3 from the high pressure tank 2 is constructed in the form of a sleeve and this is actuated between its closed and open positions by means of a crank lever and control rod 12 extending upwardly through insulator 1. A control rod 14 also extending upwardly through insulator 1 in conjunction, with a crank lever, functions to actuate the movable contact 3 studlS into and out of engagement with the stationary contact stud 15a.

MODE OF OPERATION The circuit breaker structure in accordance with the invention operates in the following manner. The operating components of the circuit breaker are indicated in the drawing in the positions they assume at the moment the contact studs 15, 15a have been separated,

extinguishing gases, e.g'., SF flowing from tank 2 into switch contact chamber 3 and through the hollow contacts studs 15, 15a into the low pressure tank 6, beingindicated' by the flow arrows. To the same extent that the gas issues from the high pressure tank 2 and flows backinto the low pressure tank 6, the interconnected pistons 5 and 7 rise so that the high'pressure tank 2 undergoes a reduction in volume while the volume of the low pressure tank 6 is increased by the same amount. The effective surfaces of the pistons 5 and 7, and the pressures in the high and low pressure tanks, are so selected that as a resultof the reduction in volume of tank 2 the pressure in-the high pressure tank 2 remains practically unchanged after the initial disconnection of the switch contacts so that compressed gas, at the same initial high pressure, is immediately available for a sec- 7 nd and rapidly following switching out, operation of the contactsafter the contacts have been automatically re-closed after the initial" switching out I and a shortcircuit condition, for example, still persists causing the the blast valve 13 being open, and the high pressure are contacts tobe opened a second time.'Ult imately, automatic operation of the compressor will function to replenish and restore the gas in the high pressure tank 2 to its initial volume and pressure but the time lag involved in putting the compressor into operation exceeds the time interval between rapid successive switchingout operations and hence necessitates other and more rapidly responsive measures, as in accor dance with the present invention to effect an immediate restoration of the gas pressure in the high pressure readinesstank'2. The time lag inthe compressor response may extend over'several off-on' switch operations so that the compressor is not put into operation until after two or more switching out operations have taken place.

We claim:

1. in a columnar type electrical circuit-breaker, the combination comprising an insulating support column, a high pressure readiness tank located at the upper end of said column containing a pressurized arc quenching gas, a switching chamber located adjacent said high pressure readiness tank, said switching chamber enclosing a pair of contacts arranged to be engaged and disengaged, a blast valve which when actuated to open position admits pressurized gas from said readiness tank into said switching chamber for extinguishing the arc drawn in the gap between said contacts as they are disengaged, a low pressure tank located adjacent said high pressure tank and which is connected with said switching chamber for receiving the gas after traversing the gap between said contacts, said high pressure tank including a cylinder portion having a piston operating therein, said piston forming an end wall 'of said cylinder and determining the overall volume of said high pressure tank, said low pressure tank including a movable outer wall operating as a piston and which determines the overall volume of said low pressure tank, and means connecting said pistons for operation conjointly such that a given increase in the volume of said low pressure tank by the gas discharged thereinto from said switching chamber is accompanied by a like decrease in volume of said high pressure tank thereby to maintain the pressure of the gas in said high pressure tank.

2.'A columnar type circuit breaker as defined in claim 1 wherein said movable outer wall of said low pressure tank has a bell-shaped configuration and is mounted for sliding movement on a fixed wall portion thereof and wherein a rolled hose diaphragm intercon- 

1. In a columnar type electrical circuit breaker, the combination comprising an insulating support column, a high pressure readiness tank located at the upper end of said column containing a pressurized arc quenching gas, a switching chamber located adjacent said high pressure readiness tank, said switching chamber enclosing a pair of contacts arranged to be engaged and disengaged, a blast valve which when actuated to open position admits pressurized gas from said readiness tank into said switching chamber for extinguishing the arc drawn in the gap between said contacts as they are disengaged, a low pressure tank located adjacent said high pressure tank and which is connected with said switching chamber for receiving the gas after traversing the gap between said contacts, said high pressure tank including a cylinder portion having a piston operating therein, said piston forming an end wall of said cylinder and determining the overall volume of said high pressure tank, said low pressure tank including a movable outer wall operating as a piston and which determines the overalL volume of said low pressure tank, and means connecting said pistons for operation conjointly such that a given increase in the volume of said low pressure tank by the gas discharged thereinto from said switching chamber is accompanied by a like decrease in volume of said high pressure tank thereby to maintain the pressure of the gas in said high pressure tank.
 2. A columnar type circuit breaker as defined in claim 1 wherein said movable outer wall of said low pressure tank has a bell-shaped configuration and is mounted for sliding movement on a fixed wall portion thereof and wherein a rolled hose diaphragm interconnects said movable and fixed wall portions to provide a sealed joint therebetween.
 3. A columnar type circuit breaker as defined in claim 1 and which further includes linkage means extending from said interconnected pistons through said insulating column for starting up a compressor interconnected between said low and high pressure tanks for re-pressuring gas taken from said low pressure tank and delivering it into said high pressure tank. 